I began work on this project in 1975, when I became a research student at Trinity Hall, Cambridge. The study was completed with the assistance of a research bye-fellowship at Girton College and a research fellowship at Jesus College, Cambridge. I wish to thank the fellows of these Colleges for the generous support which I have received.

I should like to express my gratitude to Professors Ricoeur and Habermas for their willingness to respond to my numerous inquiries. While defending many of their concerns, I have also tried to reflect critically on their work, to think in accordance with their ideas. I hope that the results of this attempt do justice to the richness of their thought.

Discussions with friends and colleagues have helped me to clarify my views. David Held and William Outhwaite read all of the manuscript and made many valuable comments. I have also benefited from conversations with Mary Hesse, Jonathan Dancy and Mike Barfoot. Any errors that remain are, of course, my own.

Above all, I offer my thanks to Anthony Giddens, who supervised the Ph.D. thesis upon which this study is based. There is no doubt that, without his constant encouragement and advice, I would have produced a very different and far inferior piece of work. Anyone who is familiar with his writings will recognise the magnitude of my debt.